Canavan disease is a rare genetic disease that results in progressive damage to brain cells. It is most common among Ashkenazi Jews.
Genetics Home Reference noted that the incidence of Canavan disease among Ashkenazi Jews is one in 6,400 to 13,500 individuals. It is unknown what the incidence of the disorder in other populations are.
The condition is caused by mutations of the ASPA gene. Normally, the ASPA gene is involved in the production of aspartoacylase, an enzyme that breaks down N-acetyl-L-aspartic acid, or NAA.
The purpose is NAA is not fully known, but Genetics Home Reference stated that it might be involved in the production of myelin, which covers nerve cells.
For an individual to have Canavan disease, she must receive an affected gene from each parent.
The mutations in Canavan disease affect the normal breakdown of NAA, which results in damage to the myelin. Without proper myelin sheath around the nerve cells, the cells cannot communicate properly.
The brain degenerates, with the brain looking like spongy tissue with microscopic fluid-filled spaces, according to the National Institute of Neurological Disorders and Stroke.
The symptoms of Canavan disease first appear around ages 3 to 6 months. MedlinePlus noted that the disease may first be noticed when the child does not meet certain developmental milestones.
The child may have issues controlling her head, increasing head size, abnormal posture with straight legs and flexed arms, and poor muscle control, especially poor control of the neck muscles. Nasal regurgitation may occur, in which there is a backflow of food that goes into the nose.
Reflux with vomiting, swallowing difficulties and feeding problems may occur. Other symptoms of Canavan disease include irritability, blindness, seizures, poor visual tracking, and severe intellectual and development disability.
Prognosis for Canavan disease is poor. The National Institute of Neurological Disorders and Stroke noted that usually, individuals with the disease die before age 10. However, some individuals survive into their twenties.